Radioisotopes used for prostate cancer treatment are predominately photon/gamma-emitters (I-125, Pd-103, Ir-192). Both temporary and permanent gamma-emitting radioseeds have gained acceptance for interstitial implantation in the prostate. Due to greater tissue penetration, however, gamma radiation can cause side effects in the patient such as gastrointestinal discomfort, can cause damage to healthy tissues outside the prostate, and can be hazardous to hospital personnel and family members. The objective of this Phase I research is to demonstrate the feasibility of using timed-bioresorbable glass matrices to encapsulate high energy, beta-emitting radioisotopes such as Y-90. Ideally, seeds from such glasses will not leak radioactivity within 10 half-lives, and will be completely bioresorbed at a predetermined rate. Timed-bioresorbable radioseeds have the advantages of (a) simple outpatient implantation procedures; (b)sparing healthy tissue while delivering a high dose to the tumor; and (c) minimal or no health hazards or side effects, since all of the beta energy is deposited within 8-9 mm in tissue. In addition, chemoprevention agents can be incorporated into the timed-bioresorbable matrix so that their release over time will help to prevent the reoccurrence of the cancer. If successful, timed-bioresorbable glass radioseeds will be a low cost alternative to permanent seeds, and will positively impact radiation therapy of prostate and other cancers. PROPOSED COMMERCIAL APPLICATIONS: Bioresorbable radioseeds hold a great deal of promise for the treatment of solid tumors and for effecting a variety of other localized radiation therapies. In addition, the bioresorbable seeds would be capable of delivering chemoprevention agents to the site of the tumor as on-going clinical trials show such agents to be of value.